The proposed study will focus on control of ion and water content in red blood cells with emphasis on mechanisms of volume regulation. This study will: 1) Investigate mechansism of cell volume regulation in human (high-K) and dog (low-K) red blood cells. 2) Characterize abnormal volume regulation in pathological red blood cells. 3) Examine trans-membrane reducing systems in red blood cells of various species. 4) Explore the feasibility of red blood cell ghosts as vehicles for procoagulation therapy. 5) Address the interactions between certain drugs and membrane transport processes.